Cuthbert of Lindisfarne (/ˈkʌθ.bɜːrt/) (c. 634 – 20 March 687) was a saint of the early Northumbrian church in the Celtic tradition. He was a monk, bishop and hermit, associated with the monasteries of Melrose and Lindisfarne in the Kingdom of Northumbria, today in north-eastern England and south-eastern Scotland. Both during his life and after his death, he became a popular medieval saint of Northern England, with a cult centred on his tomb at Durham Cathedral. Cuthbert is regarded as the patron saint of Northumbria. His feast days are 20 March (Catholic Church, Church of England, Eastern Orthodox Church, Episcopal Church) and 4 September (Church in Wales, Catholic Church).

Cuthbert grew up in or around Lauderdale, near Old Melrose Abbey, a daughter-house of Lindisfarne, today in Scotland. He decided to become a monk after seeing a vision on the night in 651 that Aidan, the founder of Lindisfarne, died, but he seems to have experienced some period of military service beforehand. He was made guest-master at the new monastery at Ripon, soon after 655, but had to return with Eata of Hexham to Melrose when Wilfrid was given the monastery instead. About 662 he was made prior at Melrose, and around 665 went as prior to Lindisfarne. In 684 he was made bishop of Lindisfarne, but by late 686 he resigned and returned to his hermitage as he felt he was about to die. He was probably in his early 50s.

Cuthbert was born (perhaps into a noble family) in Dunbar, then in Anglo-Saxon Northumbria, and now in East Lothian, Scotland, in the mid-630s, some ten years after the conversion of King Edwin of Northumbria to Christianity in 627, which was slowly followed by that of the rest of his people. The politics of the kingdom were violent, and there were later episodes of pagan rule, while spreading understanding of Christianity through the kingdom was a task that lasted throughout Cuthbert's lifetime. Edwin had been baptised by Paulinus of York, a Roman who had come with the Gregorian mission from Rome, but his successor Oswald also invited Irish monks from Iona to found the monastery at Lindisfarne where Cuthbert was to spend much of his life. This was around 635, about the time Cuthbert was born.

The tension between the Roman and Celtic Christianity, often exacerbated by Cuthbert's near-contemporary Wilfrid, an intransigent and quarrelsome supporter of Roman ways, was to be a major feature of Cuthbert's lifetime. Cuthbert himself, though educated in the Celtic tradition, followed his mentor Eata in accepting the Roman forms, apparently without difficulty, after the Synod of Whitby in 664. The earliest biographies concentrate on the many miracles that accompanied even his early life, but he was evidently indefatigable as a travelling priest spreading the Christian message to remote villages, and also well able to impress royalty and nobility. Unlike Wilfrid, his style of life was austere, and when he could, he lived the life of a hermit, though still receiving many visitors.

In Cuthbert's time the Kingdom of Northumbria included, in modern terms, northern England as well as parts of south-eastern Scotland as far north as the Firth of Forth. Cuthbert may have been from the neighbourhood of Dunbar at the mouth of the Firth of Forth in modern-day Scotland, though The Lives of the Fathers, Martyrs and Other Principal Saints ("Butler's Lives"), by Alban Butler records that he was fostered as a child near Melrose. Fostering is possibly a sign of noble birth, as are references to his riding a horse when young. One night while still a boy, employed as a shepherd, he had a vision of the soul of Aidan being carried to heaven by angels, and later found out that Aidan had died that night. Edwin Burton finds it a suggestion of lowly parentage that as a boy he used to tend sheep on the hills near that monastery. He appears to have undergone military service, but at some point he joined the very new monastery at Melrose, under the prior Boisil. Upon Boisil's death in 661, Cuthbert succeeded him as prior. Cuthbert was possibly a second cousin of King Aldfrith of Northumbria (according to Irish genealogies), which may explain his later proposal that Aldfrith should be crowned as monarch.

Cuthbert's fame for piety, diligence, and obedience grew. When Alchfrith, king of Deira, founded a new monastery at Ripon, Cuthbert became its praepositus hospitum or guest master under Eata. When Wilfrid was made abbot of the monastery, Eata and Cuthbert returned to Melrose. Illness struck the monastery in 664 and while Cuthbert recovered, the prior died and Cuthbert was made prior in his place. He spent much time among the people, ministering to their spiritual needs, carrying out missionary journeys, and preaching.

After the Synod of Whitby, Cuthbert seems to have accepted the Roman customs, and his old abbot Eata called on him to introduce them at Lindisfarne as prior there. His asceticism was complemented by his charm and generosity to the poor, and his reputation for gifts of healing and insight led many people to consult him, gaining him the name of "Wonder Worker of Britain". He continued his missionary work, travelling the breadth of the country from Berwick to Galloway to carry out pastoral work and founding an oratory at Dull, Scotland, complete with a large stone cross, and a little cell for himself. He is also said to have founded St Cuthbert's Church in Edinburgh.

Cuthbert retired in 676, moved by the desire for a more contemplative life. With his abbot's leave, he moved to a spot which Archbishop Eyre identifies with St Cuthbert's Island near Lindisfarne, but which Raine thinks was near Holburn, at a place now known as St Cuthbert's Cave. Shortly afterwards, Cuthbert moved to Inner Farne island, two miles from Bamburgh, where he gave himself up to a life of great austerity. At first he received visitors, but later he confined himself to his cell and opened his window only to give his blessing. He could not refuse an interview with the holy abbess and royal virgin Elfleda, the daughter of Oswiu of Northumbria, who succeeded St Hilda as abbess of Whitby in 680. The meeting was held on Coquet Island, further south.